Systems and methods for adjusting a sleep schedule of a wireless device in a wireless network

Abstract

Systems and methods are described for adjusting a sleep schedule of a wireless device in a wireless network. A mobility of a wireless device may be determined to exceed a threshold mobility. The wireless device may be operating in a sleep mode with a discontinuous reception schedule having listening intervals separated by sleep periods. A source access node may request to handover the wireless device to a target access node and may provide information to the target access node regarding the determined mobility and the determined sleep mode before handover completion. The target access node may then initiate wireless communication with the wireless device during a listening interval previously scheduled by the source access node. After the initial communication with the target access node, the wireless device may resume the previously determined sleep mode in order to optimize power use of the wireless device.

What is claimed is: 
     
       1. A method for adjusting a sleep schedule of a wireless device in a wireless network, the method comprising:
 determining that a mobility of the wireless device exceeds a threshold mobility, wherein determining the mobility of the wireless device is based on a number of handover requests over a time period; 
 determining by a source access node that the wireless device is operating in a first sleep mode having a first discontinuous reception schedule with first reception intervals separated by first sleep periods prior to handover; 
 determining application requirements and power conditions of the wireless device; 
 performing a handover of the wireless device from the source access node to a target access node; 
 determining by the source access node a first timer comprising an amount of time that the wireless device was in the first sleep mode prior to the handover, wherein determining the first timer further comprises subtracting an adjustment factor from the first timer based on the determined application requirements and power conditions of the wireless device; 
 providing by the source access node to the target access node information regarding the determined mobility, the determined first timer, and the determined first sleep mode prior to finishing the handover; 
 initiating wireless communication between the target access node and the wireless device during a scheduled first reception interval of the first discontinuous reception schedule; 
 resuming the first sleep mode in communication with the target access node according to a second discontinuous reception schedule based on the information provided by the source access node regarding the determined mobility and the determined first sleep mode of the wireless device; and 
 instructing the target access node to adjust the second discontinuous reception schedule based on the determined application requirements and power conditions. 
 
     
     
       2. The method of  claim 1 , further comprising:
 transitioning the wireless device to a second sleep mode after a first threshold period of inactivity, wherein during the second sleep mode, each reception interval is separated from each adjacent reception interval by a longer sleep period than the sleep periods used to separate reception intervals of the first sleep mode; and 
 providing information regarding determined mobility upon resumed communication with the target access node and the second sleep mode prior to handover to another target access node. 
 
     
     
       3. The method of  claim 1 , wherein determining the mobility of the wireless device is further based on a number of successful handovers performed over the time period. 
     
     
       4. The method of  claim 1 , wherein adjusting the second discontinuous reception schedule further comprises
 adjusting by the target access node a second timer, wherein the second timer comprises the first timer in addition to an amount of time that the wireless device has been in the first sleep mode after the handover. 
 
     
     
       5. The method of  claim 4 , wherein determining the first timer further comprises adding an amount of estimated time required to perform the handover from the source access node to the target access node. 
     
     
       6. The method of  claim 5 , wherein the amount of estimated time required to perform the handover is based on previous handover events from the source access node to the target access node. 
     
     
       7. The method of  claim 1 , wherein the adjustment factor is smaller when application requirements indicate an ability to tolerate delays. 
     
     
       8. The method of  claim 1 , wherein the adjustment factor is larger when the power conditions indicate that the wireless device has a battery level above a threshold power level or that the wireless device is connected to an external power supply. 
     
     
       9. A system for adjusting a sleep schedule of a wireless device in a wireless network, the system comprising:
 a source access node in wireless communication with a wireless device; and 
 a processor coupled to the source access node, wherein the processor is configured to: 
 determine that a mobility of the wireless device exceeds a threshold mobility, wherein determining the mobility of the wireless device is based on a number of handover requests over a time period; 
 determine that the wireless device is operating in a first sleep mode having a first discontinuous reception schedule prior to handover; 
 determine application requirements and power conditions of the wireless device; 
 perform a handover of the wireless device to a target access node; 
 determine a first timer comprising an amount of time that the wireless device was in the first sleep mode prior to the handover, wherein determining the first timer further comprises subtracting an adjustment factor from the first timer based on the determined application requirements and power conditions of the wireless device; and 
 provide to the target access node information regarding the determined mobility, the determined first timer, and the determined first sleep mode prior to finishing the handover; 
 and the target access node is configured to: 
 initiate wireless communication with the wireless device during a scheduled reception interval of the first discontinuous reception schedule; 
 resume the first sleep mode in further communication between the target access node and the wireless device using a second discontinuous reception schedule based on the information provided by the source access node regarding the determined mobility and the determined first sleep mode of the wireless device; and 
 adjust the second discontinuous reception schedule based on the determined application requirements and power conditions. 
 
     
     
       10. The system of  claim 9 , wherein the target access node is further configured to:
 transition the wireless device to a second sleep mode after a first threshold period of inactivity, wherein during the second sleep mode, each reception interval is separated from each adjacent reception interval by a longer sleep period than the sleep periods used to separate reception intervals of the first sleep mode; and 
 provide information regarding determined mobility to a second target access node. 
 
     
     
       11. The system of  claim 9 , wherein the processor is further configured to determine the mobility of the wireless device based on a number of successful handovers performed over the time period. 
     
     
       12. The system of  claim 9 ,
 wherein the target access node is further configured to: 
 adjust a second timer, wherein the second timer comprises the first timer in addition to an amount of time that the wireless device has been in the first sleep mode after handover. 
 
     
     
       13. The system of  claim 12 , wherein the first timer further comprises an amount of estimated time required to perform the handover from the source access node to the target access node. 
     
     
       14. The system of  claim 13 , wherein the amount of estimated time required to perform the handover is based on previous handover events from the source access node to the target access node. 
     
     
       15. The system of  claim 9 , wherein the adjustment factor is smaller when application requirements indicate an ability to tolerate delays. 
     
     
       16. The system of  claim 9 , wherein the adjustment factor is larger when the power conditions indicate that the wireless device has a battery level above a threshold power level or that the wireless device is connected to an external power supply.